The present invention is generally directed to toner processes, and more specifically, to chemical processes wherein there is accomplished the aggregation of latex, colorant particles, and optional additives to enable toner compositions. More specifically, the present invention is related to the direct in-situ chemical preparation of toner compositions without the need for conventionally known toner pulverization and classification methods, and wherein in embodiments toner compositions with a volume average diameter of from about 1 to about 25, and preferably from 2 to about 10 microns, and narrow particle size distribution as conventionally characterized by GSD (geometric standard deviation) of, for example, less than 1.35, more specifically, less than about 1.25, and, for example, from about 1.15 to about 1.25, as measured on the Coulter Counter, and which toners possess tunable gloss characteristics, for example from low, about 10 to about 80 Gardner Gloss units (GGU), can be obtained. The resulting toners can be selected for known electrophotographic processes and printing processes, including digital processes, and particularly color xerographic imaging and printing processes. The invention toners are particularly useful for the development of colored images with excellent (1) image resolution, (2) high color fidelity, (3) gloss uniformity, and (4) acceptable projection efficiency.
The image gloss characteristics of the toner compositions of the present invention in embodiments can be controlled primarily by the amount of the crosslinked polymer core particles, crosslink density, and composition. Specifically, lower image gloss levels of for example less than about 30, for example about 5 to about 30 GGU are obtained from toners with higher contents for example about 20 weight percent of crosslinked polymer core particles. Accordingly, a wide range of image gloss level ranging from below about 20 to in excess of about 70 GGU as measured by the Gardner Gloss metering instrument can be designed to provide specific image appearance requirements. In general, the image gloss requirement of a document is dictated by its application; for example, for process color, glossy images are highly desirable. For text, highlight and graphic documents, a matte image finish is generally preferred.
More specifically toners prepared in accordance with the present invention enable in embodiments the generation of high quality images with specifically preselected image gloss levels, and lower toner fusing temperatures, such as from about 120.degree. C. to about 170.degree. C., thereby eliminating or minimizing paper curl while prolonging the life of fuser rolls.
In color xerographic systems, small sized toners of preferably from about 2 to about 7 microns are important to the achievement of high image quality for process color applications. It is also important to have a low image pile height to eliminate image feel and avoid, or minimize paper curling after fusing. Paper curling can be particularly pronounced in xerographic color processes in which relatively high toner coverage as a result of the application of three to four color toners. During the fusing step, moisture is driven off from the paper due to high fusing temperatures of from about 120.degree. C. to 200.degree. C. With only one layer of toner, such as in one-color black or highlight color xerographic applications, the amount of moisture driven off during fusing can usually be reabsorbed back by the paper and the resulting print remains relatively flat with minimal paper curl. In process color processes where toner coverage is high, the relatively thick toner plastic covering on the paper can inhibit the paper from reabsorbing the moisture, and lead to substantial paper curling. These and other imaging shortfalls and problems are avoided or minimized with the toners and processes of the present invention.
Also, it is preferable to use small toner particle sizes, such as from about 2 to 7 microns, and with higher pigment loading, such as from about 4 to about 15 percent by weight of toner, so that the mass of toner necessary for attaining the required optical density and color gamut can be significantly reduced to eliminate or minimize image feel and paper curl.